Summer-flowering bulbs to lift in fall

Submitted to Dorchester Banner/Laetitia Sands
Bright, cheery dahlias, like many summer-flowering bulbs, should be dug up and stored in a warmish environment for the winter. Now, or very soon.

For those gardeners who don’t have enough to do at this time of year, for those who would dearly love to spend more hours outdoors, no matter how chilly or wet the weather, check to see if you have any summer-blooming bulbs in the ground that should be dug up and stored inside for the winter.

Not that I mean to sound flippant. My unspoken (written) assumption is that all gardeners want ways to reduce their workload. We feel, sometimes, like over-burdened donkeys.

In fact, many passionate plant lovers may feel a burning desire to grow certain lovely flowers, even if the plants demand more labor.

Some plants that grow from bulbs and produce attractive flowers in summer are so tender (meaning the opposite of cold-hardy) that they will die of cold if left outdoors once the temperature gets bitter enough for frost. No good gardener could countenance that! And now is the season to hop to it and dig up these tender bulbs for winter storage.

Which bulbs and how to store them? The sources I’ve consulted say “many” summer-flowering bulbs need to be lifted in fall. But quite a few of such bulbs can stay in place for years on end. Take lilies, for example. All modern hybrids are hardy, according to experts.

But calla lilies, which by the way bloom for 10 to 12 weeks, should come out of the ground and go into storage at a temperature of 40 to 50 F until all danger of frost has passed. The same applies to gloriosa, a.k.a. glory lily or climbing lily. However, it needs a temperature of between 55 and 60 F in its winter retreat.

One could say that when in doubt, check the package the bulbs came in and hope that the advice given on whether or not to lift them in fall is correct.

Backtracking just a bit: What exactly is meant by “bulb?” In this context, the term covers all sorts of strange-looking, lumpy root structures, be they corms, rhizomes, tubers, tuberous roots or true bulbs, which resemble light bulbs in shape, with roots coming out of the bottom. As for “summer,” it means the period from June to September.

The bulbs most gardeners will think of as needing to be stored inside for winter include: begonias, caladiums, canna, crocosmias, dahlias, gladiolas and freesias. Some others to add to the list: Acidantheras, a close relative of gladiola, achimenes (or magic flower), tuberoses and galtonia (summer hyacinth).
Digging is only the first step. Bulbs have different demands as to their storage temperature. Dahlias like a bracing 40 to 45 degrees.

If their environment warms much above 45 or 50, they may sprout prematurely or rot. Tuberous begonias and gladiolas prefer 40 to 50 degrees, caladiums and galtonia 55 to 60, achimenes 60 degrees and tuberoses 55 to 65. Achimenes need special care: A storage temperature colder than 55 can kill them and they should be lifted in October, without fail.

As for how long the gardener has to dig up these summer-flowering bulbs before a frost hits in our county, Freeze-Date Tables in the University of Maryland Master Gardener’s Handbook say there’s a 67 percent chance of Cambridge getting a frost by Nov. 1 – about two weeks from now.

This means that in two out of three years, a frost had hit by that date. There’s a 90 percent likelihood that a frost will have occurred by Nov. 10.

Generally, it’s wise to remove bright, cheery dahlias, like many summer-flowering bulbs, should be dug up and stored in a warmish environment for the winter. Now, or very soon. such bulbs from the ground only after their leaves have turned yellow. Of course, this year most of our plants turned brown weeks ago, without going through the yellow stage, due to drought.

Leave the soil on achimenes, begonia, canna, caladium and dahlia bulbs. Store them in clumps on a slightly moistened layer of peat moss or sawdust, and put them in a dry cellar, shed, garage or room where the winter temperature matches their requirements and they’re away from direct light.

Other sorts of bulbs should be rinsed off, then spread in a shady spot to dry, which usually takes one to three days. Then they can be put in a sack (with some ventilation), mesh bag, paper bag or old nylon stockings and hung in the place chosen for storage. Some gardeners add dry peat moss, vermiculite or perlite to keep the bulbs separate.

It’s important that they have air circulating so they don’t go moldy, so stay away from plastic bags. Also, never store bulbs more than two layers deep because bulbs generate heat, which could cause decay.

If you open the bags in spring and find some bulbs covered in blue mold, wipe them off with a wet towel and plant them anyway. They may grow with no trouble.

A word on gladioli: Lift the corms out of the ground with a spading fork, cut off the tops and let them dry in a shallow container set in an airy place, out of the sun, for two or three weeks. Then pull off any remnants of the dry corms.

Save both the corms and “cormels” at their bases and put them in a stocking or ventilated bag. The cormels, once planted, should flower in two years’ time.

You may want to dust gladiola corms with a mix of insecticide and fungicide before storing them; but personally, I prefer to steer away from chemicals, particularly if they’re likely to kill insects, whose population has plummeted worldwide in recent years.

These tender, summer-flowering bulbs should be taken out of storage and planted next spring, when there’s no longer any danger of frost.
In the meantime, happy gardening!
Editor’s Note: Laetitia Sands is a master gardener in Dorchester County.

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